I've never messed with PPC stuff other than adsense. With blogs, you aren't going to make much with a single site. Not right away and then only if you really know what you are doing.
It's much easier to run as many of them as you can stand to do. Build some that have unique posts on them, and then build even more that are fed with RSS feeds.
You need to think in bulk. Check out this thread, I just posted some info there.
http://www.gofuckyourself.com/showthread.php?t=796100